Name krypton
Symbol Kr
Atomic Weight 83.80
Atomic Number 36
CAS ID 7439-90-9
Group Number 18
Group Name Noble Gas
Period Number 4
Origin of Name From the Greek, kryptos = "hidden."
Year Discovered 1898
Discovery Credits Discovered by Sir William Ramsay and M. W. Travers at London, UK.
Class Non-Metallic
Color Colorless
Standard State Gas at 77 F & 298 K
Description Colorless, odorless gas present in the atmosphere. Chemically inert to everything but fluorine.  86Kr has an orange-red line in its atomic spectrum that is used for the SI length standard where 1 meter = 1,650,763.73 wavelengths. One meter was originally defined as 1 millionth the distance from the earth's pole to the equator.

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